| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a unit and method wherein a brake and the like does not operate even when a smoothing capacitor is made compact, and a motor can be driven in a highly efficient and smooth fashion. <P>SOLUTION: In a motor drive, a predicted value Va of the terminal voltage of the motor and an intermediate DC voltage Vdc are compared (111); when Va>Vdc, a value minimally increased from the set value of a d-axis current in the previous power cycle (102, 103) is selected (104) and used as the set value of the d-axis current; whereas when Va<Vdc, the set value of the d-axis current that is proportional to the square of the intermediate DC voltage Vdc (106) is selected (104) and used as the set value of the d-axis current. By this means, a q-axis current pattern or a torque pattern becomes proportional to the square of the intermediate DC voltage so that the brake does not operate even when the capacity of the smoothing capacitor is small and the voltage drops substantially, and a drive that has high average drive efficiency and becomes stable with respect to power source voltage fluctuations is achieved. <P>COPYRIGHT: (C)2003,JPO |
